Use of dual H3/M2 antagonists in the treatment of cognition deficit disorders

ABSTRACT

This invention relates to a method of treating cognition deficit disorders comprising administering to a mammal in need of such treatment an effective amount of a dual histamine H 3  receptor antagonist/m 2  muscarinic antagonist, or a combination of a histamine H 3  receptor antagonist and a m 2  muscarinic antagonist.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 60/267,352, filed Feb. 8, 2001.

BACKGROUND

[0002] This invention relates to the treatment of cognition deficit disorders by administering a dual histamine H₃ receptor antagonist/m₂ muscarinic antagonist, or a combination of an histamine H₃ receptor antagonist and a m₂ muscarinic antagonist. In particular, the invention relates to the treatment of cognition deficit diseases such as Alzheimer's Disease (AD) or other CNS learning disorders such as attention deficit disorder and autism.

[0003] European Patent Application No. 0 420 396 A2 and Howson et al., Bioorg. & Med. Chem. Letters, Vol. 2 No. 1 (1992), pp. 77-78, describe imidazole derivatives having an amidine group as H₃ agonists. Van der Groot et al. (Eur. J. Med. Chem. (1992) Vol. 27, pp. 511-517) describe isothiourea analogs of histamine as potent agonists or antagonists of the histamine H₃ receptor, and these isothiourea analogs of histamine overlap in part with those of the two references cited above. Clapham et al, J. Psychopharmacol. (British Assn. for Psychopharmacology, Jul. 25-28 1993, Abstr. Book), A17] describes the ability of histamine H₃ receptor antagonists to improve cognition and to increase release of acetylcholine in vivo in the rat. Clapham et al., Brit. J. Pharm. Suppl., 1993, 110, Abstract 65P, presents results showing that thioperamide can improve short-term memory and reversal learning in the rat and implicate the involvement of H₃ receptors in the modulation of cognitive function. Yokoyama et al, Eur. J. Pharmacol., vol. 234 (1993), pp. 129-133, reports how thioperamide decreased the duration of each phase of convulsion and raised the electroconvulsive threshold, and go on to suggest that these and other findings support the hypothesis that the central histaminergic system is involved in the inhibition of seizures. WO 9301812-A1 describes the use of S-[3-(4(5)-imidazolyl) propyl]-isothiourea as a histamine H₃ antagonist, especially for treating cognitive disorders, e.g. Alzheimer's disease and age-related memory impairment. Schlicker et al. describe a number of imidazolylalkyl compounds wherein the imidazolylalkyl group is bonded to a guanidine group, an ester group or an amide group (including thioamide and urea), and compare these to thioperamide. Leurs et al., Progr. Drug Res. (1992) vol. 39, pp. 127-165, and Lipp et al. The Histamine Receptor, eds.: Schwartz and Haas, Wiley-Liss, New York (1992), pp. 57-72, review a variety of synthetic H₃ receptor antagonists, and Lipp et al. (ibid. ) have defined the necessary structural requirements for an H₃ receptor antagonist.

[0004] Several muscarinic receptor subtypes have been identified, i.e., m₁, m₂, m₃, m₄ and m₅, and the potential therapeutic effects of the various subtypes have been the subject of many publications. See, for example, U.S. Pat. No. 5,446,057, wherein the m₁ receptor was identified as mediating gastric secretion; m₂ and m₃ receptors were identified as mediating nasal mucosal secretions; and m₂ was identified as mediating cardiovascular conditions and CNS conditions associated with release of acetylcholine, e.g., Alzheimer's disease and other dementias. Muscarinic receptors in general were reported to be mediators of cholinergic neurotransmission.

SUMMARY OF THE INVENTION

[0005] This invention relates to a method of treating cognition deficit disorders comprising administering to a mammal in need of such treatment an effective amount of a dual histamine H₃ receptor antagonist/m₂ muscarinic antagonist, or a combination of an histamine H₃ receptor antagonist and a m₂ muscarinic antagonist. In particular, the method relates to the treatment of Alzheimer's Disease, attention deficit disorder or autism comprising administering an effective amount of a dual H₃/m₂ antagonist, or a combination of an H₃ antagonist and a m₂ antagonist.

[0006] The dual H₃/m₂ antagonist compounds of the invention are preferably administered as a pharmaceutical composition comprising the dual antagonist and a pharmaceutically acceptable carrier. When separate H₃ and m₂ antagonists are used in combination, an effective amount of the combination of a H₃ antagonist and a m₂ antagonist can be combined with a pharmaceutically acceptable carrier in a single pharmaceutical composition. Alternatively, a pharmaceutical composition comprising a H₃ antagonist and a separate pharmaceutical composition comprising a m₂ antagonist can be administered, simultaneously or sequentially, wherein the individual antagonists are administered in amounts chosen so that the combination is effective to treat cognition deficit disorders. Kits comprising separate H₃ and m₂ pharmaceutical compositions in a single package are also contemplated.

[0007] In still another aspect, the invention relates to a method for treating a cognitive disease or neurodegenerative disease comprising administering to a mammal in need of such treatment an effective amount of a dual histamine H₃ receptor antagonist/m₂ muscarinic antagonist, or a combination of an histamine H₃ receptor antagonist and a m₂ muscarinic antagonist, in further combination with an acetylcholinesterase inhibitor. Pharmaceutical compositions comprising a dual histamine H₃ receptor antagonist/m₂ muscarinic antagonist and an acetylcholinesterase inhibitor in a pharmaceutically acceptable carrier, or separate H₃ and m₂ antagonists and an acetylcholinesterase inhibitor in a pharmaceutically acceptable carrier are contemplated. Kits comprising separate dual H₃/m₂ antagonist and acetylcholinesterase inhibitor pharmaceutical compositions, and separate H₃, m₂ and acetylcholinesterase inhibitor pharmaceutical compositions in a single package are also contemplated.

DETAILED DESCRIPTION

[0008] Dual H₃/m₂ antagonists of the present invention are exemplified by the compounds shown in the following table: Compound Number Structure 1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

[0009] Other compounds having dual H₃/m₂ antagonist activity can be identified by evaluating the compounds for activity at H₃ receptors and activity at m₂ receptors using the test methods described below.

[0010] The currently known histamine H₃ receptor antagonists cannot be easily classified chemically, but include, without limitation: thioperamide, impromidine, burimamide, clobenpropit, impentamine, mifetidine, clozapine, S-sopromidine, R-sopromidine, ciproxifam, SKF-91486, GR-175737, GT-2016, GT-2331 and UCL-1199.

[0011] Certain H₃ antagonists are disclosed in several US patents. U.S. Pat. No. 5,463,074 discloses the following compounds:

[0012] or a pharmaceutically acceptable salt or solvate thereof, wherein:

[0013] (A) m is an integer selected from the group consisting of: 0, 1, and 2;

[0014] (B) n and p are integers and are each independently selected from the group consisting of: 0, 1, 2, and 3 such that the sum of n and p is 2 or 3;

[0015] (C) each R¹, R², R³, R⁴, R⁶, R⁷, and R⁸ is independently selected from the group consisting of:

[0016] (1) H;

[0017] (2) C₁ to C₆ alkyl;

[0018] (3) C₃ to C₆ cycloalkyl; and

[0019] (4) —(CH₂)_(q)—R⁹ wherein q is an integer of: 1 to 7, and R⁹ is selected from the group consisting of: phenyl, substituted phenyl, —OR¹⁰, —C(O)OR¹⁰, —C(O)R¹⁰, —OC(O)R¹⁰, —C(O)NR¹⁰R¹¹, CN and —SR¹⁰ wherein R¹⁰ and R¹¹ are as defined below, and wherein the substituents on said substituted phenyl are each independently selected from the group consisting of: —OH, —O—(C₁ to C₆)alkyl, halogen, C₁ to C₆ alkyl, —CF₃, —CN, and —NO₂, and wherein said substituted phenyl contains from 1 to 3 substituents;

[0020] (D) R⁵ is selected from the group consisting of:

[0021] (1) H;

[0022] (2) C₁ to C₂₀ alkyl;

[0023] (3) C₃ to C₆ cycloalkyl;

[0024] (4) —C(O)OR^(10′); wherein R^(10′) is the same as R¹⁰ defined below except that R^(10′) is not H;

[0025] (5) —C(O)R¹⁰;

[0026] (6) —C(O)NR¹⁰R¹¹;

[0027] (7) allyl;

[0028] (8) propargyl; and

[0029] (9) —(CH₂)_(q)—R⁹, wherein q and R⁹ are as defined above with the proviso that when q is 1 then R⁹ is not —OH or —SH;

[0030] (E) R¹⁰ and R¹¹ are each independently selected from the group consisting of: H, C₁ to C₆ alkyl, and C₃ to C₆ cycloalkyl; and, for the substituent —C(O)NR¹⁰R¹¹, R¹⁰ and R¹¹, together with the nitrogen to which they are bound, can form a ring having 5, 6, or 7 atoms;

[0031] (F) the dotted line (------) represents a double bond that is optionally present when m is 1, and T is a 5-membered ring, and n is not 0, and p is not 0, and when said double bond is present then R² and R⁸ are absent;

[0032] (G) when m is 2, each R¹ is the same or different substituent for each m, and each R² is the same or different substituent for each m;

[0033] (H) when n is 2 or 3, each R³ is the same or different substituent for each n, and each R⁴ is the same or different substituent for each n; and

[0034] (I) when p is 2 or 3, each R⁶ is the same or different substituent for each p, and each R⁷ is the same or different substituent for each p.

[0035] U.S. Pat. No. 5,807,872 discloses the following compounds:

[0036] or a pharmaceutically acceptable salt or solvate thereof, wherein:

[0037] (A) m is 1 or 2;

[0038] (B) n and p are independently selected from 0, 1, 2, 3, and 4 such that the sum of n and p is 4 and T is a 6-membered ring;

[0039] (C) R³ and R⁴ are each independently bound to the same or different carbon atom of ring T such that there is only one R³ group and one R⁴ group in ring T, and each R¹, R², R³, and R⁴ is independently selected from the group consisting of:

[0040] (1) H;

[0041] (2) C₁ to C₆ alkyl; and

[0042] (3) —(CH₂)_(q)—R⁶ wherein q is an integer of: 1 to 7, and R⁶ is selected from the group consisting of: phenyl, substituted phenyl, —OR⁷, —C(O)OR⁷, —C(O)R⁷, —OC(O)R⁷, —C(O)NR⁷R⁸, CN and —SR⁷ wherein R⁷ and R⁸ are as defined below, and wherein the substituents on said substituted phenyl are each independently selected from the group consisting of: —OH, —O—(C₁ to C₆)alkyl, halogen, C₁ to C₆ alkyl, —CF₃, —CN, and —NO₂, and wherein said substituted phenyl contains 1 to 3 substituents;

[0043] (D) R⁵ is selected from the group consisting of:

[0044] (1) H;

[0045] (2) C₁ to C₂₀ alkyl;

[0046] (3) C₃ to C₆ cycloalkyl;

[0047] (4) —C(O)OR^(7′); wherein R^(7′) is the same as R⁷ defined below except that R^(7′) is not H;

[0048] (5) —C(O)R⁷;

[0049] (6) —C(O)NR⁷R⁸;

[0050] (7) allyl;

[0051] (8) propargyl; and

[0052] (9) —(CH₂)_(q)—R⁶, wherein q and R⁶ are as defined above, and when q is equal to 1, then R⁶ is not OH or SH;

[0053] (E) R⁷ and R⁸ are each independently selected from the group consisting of: H, C₁ to C₆ alkyl, and C₃ to C₆ cycloalkyl;

[0054] (F) the dotted line (------) represents a double bond that is optionally present when m is 1, and n is not 0, and p is not 0, and when said double bond is present then R² is absent; and

[0055] (G) when m is 2, each R¹ is the same or different substituent for each m, and each R² is the same or different substituent for each m, and at least two of the substituents R¹ and/or R² are H.

[0056] U.S. Pat. No. 5,633,250 discloses the following compounds:

[0057] or a pharmaceutically acceptable salt or solvate thereof, wherein:

[0058] (A) n is 1 or 2;

[0059] (B) R¹ is selected from the group consisting of:

[0060] (1) H;

[0061] (2) C₁ to C₆ alkyl;

[0062] (3) allyl; and

[0063] (4) propargyl;

[0064] (C) R³ and R⁴ are independently selected from the group consisting of:

[0065] (1) H;

[0066] (2) C₁ to C₆ alkyl;

[0067] (3) allyl;

[0068] (4) propargyl; and

[0069] (5) —(CH₂)_(q)—R⁵ wherein q is an integer of: 1 to 7, and R⁵ is selected from the group consisting of: phenyl, substituted phenyl, —OR⁶, —C(O)OR⁶, —C(O)R⁶, —OC(O)R⁶, —C(O)NR⁶R⁷, CN and —SR⁶ wherein R⁶ and R⁷ are as defined below, and wherein the substituents on said substituted phenyl are each independently selected from the group consisting of: —OH, —O—(C₁ to C₆)alkyl, halogen, C₁ to C₆ alkyl, —CF₃, —CN, and —NO₂, and wherein said substituted phenyl contains 1 to 3 substituents;

[0070] (D) R⁶ and R⁷ are each independently selected from the group consisting of: H and C₁ to C₆ alkyl; and

[0071] (E) R³ and R⁴ are each independently bound to the same or different carbon atom of ring T.

[0072] U.S. Pat. No. 5,578,616 discloses the following compounds:

[0073] Wherein:

[0074] A is selected from —O—CO—NR¹—, —O—CO—, —NR¹—CO—NR¹—, —NR¹—CO—, —NR¹—, —O—, —CO—NR¹—, —CO—O—, and —C(:NR¹)—NR¹—;

[0075] the groups R¹, which may be the same or different when there are 2 or 3 such groups in the molecule shown above, are selected from H, and lower alkyl, aryl, cycloalkyl, heterocyclic and heterocyclyl-alkyl groups, and groups of the formula —(CH₂)_(y)—G, where G is selected from CO₂R³, COR³, CONR³R⁴, OR³, SR³, NR³R⁴ heteroaryl and phenyl, which phenyl is optionally substituted by halogen, lower alkoxy or polyhaloloweralkyl, and y is an integer from 1 to 3;

[0076] R² is selected from H and halogen atoms, and alkyl, alkenyl, alkynyl and trifluoromethyl groups, and groups of the formula OR³, SR³ and NR³R⁴;

[0077] R³ and R⁴ are independently selected from H, and lower alkyl and cycloalkyl groups, or R³ and R⁴ together with the intervening nitrogen atom can form a saturated ring containing 4 to 6 carbon atoms that can be substituted with 1 or 2 lower alkyl groups;

[0078] with the proviso that, when y is 1 and G is OR³, SR³ or NR³R⁴, then neither R³ nor R⁴ is H;

[0079] the group —(CH₂)_(n)—A—R¹ is at the 3- or 4-position, and the group R² is at any free position;

[0080] m is an integer from 1 to 3; and

[0081] n is 0 or an integer from 1 to 3;

[0082] or a pharmaceutically acceptable acid addition salt thereof;

[0083] or a pharmaceutically acceptable salt thereof with a base when G is CO₂H;

[0084] including a tautomeric form thereof.

[0085] U.S. Pat. No. 6,100,279 discloses the following compounds:

[0086] or pharmaceutically acceptable salts or solvates thereof, wherein:

[0087] X is a straight chain alkyl group having 1 to 7 carbon atoms or an alkene or alkyne group with 2 to 4 carbon atoms; wherein said alkyl or alkene groups are optionally substituted with up to two R⁷ groups;

[0088] n is 0, 1 or 2,

[0089] m and p are 0 to 4;

[0090] when m is 0 to 4, Y represents —SO₂—; —CS—; —CO—; —CONR⁵—; —CO (CH₂)_(w)O—(with w being 1 to 4); —COO—; —CON(OR⁵)—; —C(NR⁵)NR⁵—; —SO₂NR⁵— or —CSNR⁵—;

[0091] when m is 2 to 4, Y represents all the groups above when m is 0 to 4 and, in addition, Y represents —CHOR⁵—; —O—; —NR⁵CONR⁵⁻; —NR⁵CO—; —NR⁵—; —OCONR⁵—; —NR⁵C(NR⁵)NR⁵⁻; —NR⁵CSNR⁵; —NR⁵CS— or —NR⁵SO₂—; —NR⁵C(O)O—; or —CSNR⁵;

[0092] each R⁵ independently represents H, alkyl or benzyl;

[0093] R⁶ represents aryl, heteroaryl, or a 3- to 7-membered heterocyclic group having one to three heteroatoms in the ring, wherein the heteroatoms are selected from N, S and O, and wherein said R⁶ group is optionally substituted by one to three substituents as defined below;

[0094] when Y is —SO₂—, then R⁶, in addition to the above groups, also represents alkyl having 1 to 7 carbon atoms or a group —NR¹⁰R¹¹ wherein R¹⁰ and R¹¹ are independently selected from H, alkyl or trihalomethyl;

[0095] each R¹ is independently H, alkyl or trihalomethyl;

[0096] each R⁷ is independently selected from H, alkyl, trihalomethyl, phenyl or benzyl, wherein said phenyl and benzyl are optionally substituted by one to three substituents independently selected from of alkyl, halogen, trihalomethyl, CN, NO₂, OR¹⁰ or NR¹⁰R¹¹, wherein R¹⁰ and R¹¹ are as above defined.

[0097] U.S. Pat. No. 6,034,251 discloses the following compounds:

[0098] or a pharmaceutically acceptable salt or solvate thereof, wherein:

[0099] the double bond (a) is E or Z;

[0100] each R¹ is independently selected from the group consisting of H, lower alkyl, trihalomethyl, phenyl and benzyl;

[0101] each R⁷ is independently selected from the group consisting of H, lower alkyl, halogen, trihalomethyl, NR¹⁰R¹¹, or a group OR¹⁰, whereby R¹⁰ and R¹¹ are independently selected from H, lower alkyl or trihalomethyl;

[0102] X is —CONR⁵—; —SO₂—, —S—; —CO—; —COO—; —CN(OR⁵)NR⁵—; —C(NR⁵)NR⁵—; —SONR⁵—; —SO₂NR⁵— and, provided p is not zero, X may also be —O—; —NR⁵—; —NR⁵CONR⁵—; —OCONR⁵—; —O—CO— or —NR⁵CO—;

[0103] Y is C₁-C₃-alkyl, optionally substituted at any carbon atom of the group by one substituent R⁵;

[0104] Z is C(R¹)₂; wherein no more than two R¹ groups are other than H;

[0105] n is 1 or 2;

[0106] m is 0 or 1;

[0107] p is 0 or 1;

[0108] q is 0 or 1;

[0109] R is selected from C₃ to C₇ cycloalkyl, heterocyclic groups, aryl or heteroaryl, wherein said R groups are optionally substituted with 1-3 substituents;

[0110] each R⁵ independently represents H, lower alkyl or poly-haloloweralkyl; and

[0111] R¹⁵ represents H or lower alkyl (e.g., methyl).

[0112] U.S. Pat. No. 5,990,147 discloses the following compounds:

[0113] or a pharmaceutically acceptable acid addition salt or solvate thereof (or tautomer thereof), wherein:

[0114] A is —CH₂—NH—CO—NH—; —CH₂—O—CO—NH— or —CH₂CH₂—CO—NH—(CH₂)_(m)—;

[0115] m is 0, 1 or 2;

[0116] R is the group

[0117] Wherein at least two of R¹, R², R³ and R⁴ are H and the two others are independently selected from H, halogen, CH₃, CF₃, OCH₃, OCF₃ or CN; and with the proviso, that when A is —CH₂—O—CO—NH— and R¹, R³ and R⁴ are all H, then R² can not be Cl.

[0118] U.S. patent application Ser. No. 09/978,267 discloses the following compounds:

[0119] or a pharmaceutically acceptable salt or solvate thereof, wherein:

[0120] (1) R¹ is selected from aryl, heteroaryl, heterocycloalkyl, alkyl, cycloalkyl, or alkylaryl; wherein said R¹ groups are optionally substituted with 1 to 4 substituents independently selected from: halogen, hydroxyl, lower alkoxy, —CF₃, CF₃O—, —NR⁴R⁵, phenyl, NO₂, —CO₂R⁴, —CON(R⁴)₂ wherein each R⁴ is the same or different, —S(O)_(m)N(R²⁰)₂ wherein each R²⁰ is the same or different H or alkyl group, or —CN; or

[0121] (2) R¹ and X taken together form a group selected from:

[0122] (3) X is selected from: ═C(O), ═C(NOR³), ═C(NNR⁴R⁵),

[0123] (4) M¹ and M² are independently selected from C or N;

[0124] (5) M³ and M⁴ are independently selected from C or N;

[0125] (6) Y is selected from: is —CH₂—, ═C(O), ═C(NOR²⁰), or ═C(S);

[0126] (7) Z is a C₁-C₆ alkyl group;

[0127] (8) R² is a five or six-membered heteroaryl ring, said heteroaryl rings being optionally substituted with 1 to 3 substituents independently selected from: halogen, hydroxyl, lower alkyl, lower alkoxy, —CF₃, CF₃O—, —NR⁴R⁵, phenyl, —NO₂, —CO₂R⁴, —CON(R⁴)₂ wherein each R⁴ is the same or different, —CH₂NR⁴R⁵, —(N)C (NR⁴R⁵)₂, or —CN;

[0128] (9) R³ is selected from H, C₁-C₆ alkyl, aryl, heteroaryl, heterocycloalkyl, arylalkyl, —(CH₂)_(e)—C(O)N(R⁴)₂ wherein each R⁴ is the same or different, —(CH₂)_(e)—C(O)OR⁴, —(CH₂)_(e)—C(O)R³⁰ wherein R³⁰ is a heterocycloalkyl group, including

[0129] —CF₃, or —CH₂CF₃;

[0130] wherein said aryl, heteroaryl, heterocycloalkyl, and the aryl portion of said arylalkyl are optionally substituted with 1 to 3 substituents selected from: halogen, —OH, —OCF₃, —CF₃, —CN, —N(R⁴⁵)₂, —CO₂R⁴⁵, or —C(O)N(R⁴⁵)₂, wherein each R⁴⁵ is independently selected from: H, alkyl, alkylaryl, or alkylaryl wherein said aryl moiety is substituted with 1 to 3 substituents independently selected from —CF₃, —OH, halogen, alkyl, —NO₂, or —CN;

[0131] (10) R⁴ is selected from: H, C₁-C₆ alkyl, aryl, alkylaryl, said aryl and alkylaryl groups being optionally substituted with 1 to 3 substituents selected from: halogen, —CF₃, —OCF₃, —OH, —N(R⁴⁵)₂, —CO₂R⁴⁵, —C(O)N(R⁴⁵)₂, or —CN; wherein R⁴⁵ is as defined above;

[0132] (11) R⁵ is selected from: H, C₁-C₆ alkyl, —C(O)R⁴, —C(O)₂R⁴, or —C(O)N(R⁴)₂ wherein each R⁴ is independently selected, and R⁴ is as defined above;

[0133] (12) or R⁴ and R⁵ taken together with the nitrogen atom to which they are bound forms a five or six membered heterocycloalkyl ring;

[0134] (13) R⁶ is selected from: alkyl, aryl, alkylaryl, halogen, hydroxyl, lower alkoxy, —CF₃, CF₃O—, —NR⁴R⁵, phenyl, —NO₂, —CO₂R⁴, —CON(R⁴)₂ wherein each R⁴ is the same or different, or —CN;

[0135] (14) R¹² is selected from: alkyl, hydroxyl, alkoxy, or fluoro;

[0136] (15) R¹³ is selected from: alkyl, hydroxyl, alkoxy, or fluoro;

[0137] (16) a is 0 to 2;

[0138] (17) b is 0 to 2;

[0139] (18) c is 0 to 2;

[0140] (19) e is 0 to 5;

[0141] (20) m is 1 or 2;

[0142] (21) n is 1, 2 or 3, with the proviso that when M¹ and M² are both nitrogen, then n is 2 or 3; and

[0143] (22) p is 1, 2 or 3, with the proviso that when M³ and M⁴ are both nitrogen, then p is 2 or 3.

[0144] U.S. Provisional Application No. 60/275,417 discloses the following compounds:

[0145] or a pharmaceutically acceptable salt or solvate thereof, wherein:

[0146] (A) R¹ is selected from aryl, heteroaryl, heterocycloalkyl, alkyl, —C(O)N(R⁴⁸)₂, cycloalkyl, arylalkyl, heteroarylheteroaryl or a group selected from:

[0147] said aryl, heteroaryl, aryl portion of arylalkyl, phenyl ring of formula II^(a), phenyl ring of formula III^(a), phenyl rings of formula IVB^(a), or phenyl rings of formula IVD^(a) are optionally substituted with 1 to 3 substituents independently selected from halogen; hydroxyl; lower alkoxy; —Oaryl; —SR²²; —CF₃; —OCF₃; —OCHF₂; —NR⁴R⁵; phenyl; NO₂; —CO₂R⁴; —CON(R⁴)₂, wherein each R⁴ is the same or different; —S(O)₂R²²; —S(O)₂N(R²⁰)₂, wherein each R²⁰ is the same or different; —N(R²⁴)S(O)₂R²²; —CN; —CH₂OH; —OCH₂CH₂OR²²; alkyl; substituted phenyl wherein said phenyl has 1 to 3 substituents independently selected from alkyl, halogen, —CN, —NO₂, —OCHF₂, —Oalkyl; —Oalkylaryl wherein said aryl group is optionally substituted with 1 to 3 independently selected halogens; or phenyl;

[0148] (B) X is selected from alkyl or —S(O)₂—;

[0149] (C) Y represents a single bond; or Y is selected from —C(O)—, —C(S)—, —(CH₂)_(q—), or —NR⁴C(O)—; with the provisos that when M¹ is N, then Y is not —NR⁴C(O)—; and when Y is a bond, then M¹ and M² are both carbon;

[0150] (D) M¹ and M² are independently selected from C or N;

[0151] (E) Z is selected from: C₁-C₆ alkyl, —SO₂—, —C(O)— or —C(O)NR⁴—;

[0152] (F) R² is selected from: a six-membered heteroaryl ring having 1 or 2 heteroatoms independently selected from N or N—O, with the remaining ring atoms being carbon; a five-membered heteroaryl ring having 1 to 3 heteroatoms selected from nitrogen, oxygen, or sulfur with the remaining ring atoms being carbon; an alkyl group; an aryl group wherein said substituted phenyl is substituted with 1 to 3 substituents independently selected from halogen, —Oalkyl, —OCF₃, —CF₃, —CN, —NO₂, —NHC(O)CH₃, or —O(CH₂)_(q)N(R^(10A))₂; —N(R^(11A))₂ wherein each R^(11A) is independently selected from H, alkyl or aryl; a group of the formula

[0153] or a heteroarylheteroaryl group;

[0154] said five membered heteroaryl ring or six-membered heteroaryl ring is optionally substituted with 1 to 3 substituents selected from halogen; hydroxyl; lower alkyl; lower alkoxy; —CF₃; —NR⁴R⁵; phenyl; —NO₂; —C(O)N(R⁴)₂ (wherein each R⁴ is the same or different); —C(O)₂R⁴; or phenyl substituted with 1 to 3 substituents independently selected from: halogen, —Oalkyl, —OCF₃, —CF₃, —CN, —NO₂ or —O(CH₂)_(q)N(R^(10A))₂;

[0155] (G) R³ is is selected from aryl; heteroaryl; heterocycloalkyl; alkyl; or cycloalkyl; wherein said aryl or heteroaryl R³ groups is optionally substituted with 1 to 3 substituents independently selected from halogen; hydroxyl; lower alkoxy; —Oaryl; —SR²²; —CF₃; —OCF₃; —OCHF₂; —NR⁴R⁵; phenyl; —NO₂; —CO₂R⁴; —CON(R⁴)₂ wherein each R⁴ is the same or different; —S(O)₂R²²; —S(O)₂N(R²⁰)₂ wherein each R²⁰ is the same or different; —N(R²⁴)S(O)₂R²²; —CN; —CH₂OH; —OCH₂CH₂OR²²; or alkyl;

[0156] (H) R⁴ is selected from hydrogen; C₁-C₆ alkyl; cycloalkyl; cycloalkylalkyl; heterocycloalkylalky; bridged bicyclic cycloalkyl ring; aryl having a fused heterocycloalkyl ring bound to said aryl ring; aryl; arylalkyl; alkylaryl; —(CH₂)_(d)CH(R^(12A))₂ wherein d is 1 to 3, and each R^(12A) is independently selected from phenyl or substituted phenyl, said substituted phenyl being substituted with 1 to 3 substituents independently selected from: halogen, —Oalkyl, —OCF₃, —CF₃, —CN, or —NO₂; heterocycloalkylheteroaryl; or —(C₁ to C₆)alkylene—O—R²²;

[0157] wherein the aryl R⁴ group, the aryl portion of the arylalkyl R⁴ group, or the aryl portion of the alkylaryl R⁴ group is optionally substituted with 1 to 3 substituents independently selected from halogen; hydroxyl; lower alkyl; lower alkoxy; —CF₃; —N(R²⁰)(R²⁴); phenyl; —NO₂; —C(O)N(R²⁰)₂ (wherein each R²⁰ is the same or different); —C(O)R²²; —(CH₂)_(k)-cycloalkyl; —(CH₂)_(q)-aryl; or —(CH₂)_(m)—OR²²;

[0158] (I) each R^(4B) is independently selected from: H, heteroaryl, alkyl, alkenyl, a group of the formula

[0159] arylalkyl, or arylalkyl wherein the aryl moiety is substitued with 1-3 substituents independently selected from: halogen;

[0160] (J) R⁵ is selected from: hydrogen, C₁-C₆ alkyl, —C(O)R²⁰, —C(O)₂R²⁰, —C(O)N(R²⁰)₂ (wherein each R²⁰ is the same or different);

[0161] (K) each R^(10A) is independently selected from H or C₁ to C₆ alkyl, or each R^(10A), taken together with the nitrogen atom to which they are bound, forms a 4 to 7 membered heterocycloalkyl ring;

[0162] (L) R¹² is selected from alkyl, hydroxyl, alkoxy, or fluoro, provided that when R¹² is hydroxy or fluoro then R¹² is not bound to a carbon adjacent to a nitrogen; or R¹² forms an alkyl bridge from one ring carbon to another ring carbon;

[0163] (M) R¹³ is selected from alkyl, hydroxyl, alkoxy, or fluoro, provided that when R¹³ is hydroxy or fluoro then R¹³ is not bound to a carbon adjacent to a nitrogen; or R¹³ forms an alkyl bridge from one ring carbon to another ring carbon;

[0164] (N) R²⁰ is selected from hydrogen, alkyl, or aryl, wherein said aryl group is optionally substituted with from 1 to 3 groups independently selected from: halogen, —CF₃, —OCF₃, hydroxyl, or methoxy; or when two R²⁰ groups are present, said two R²⁰ groups taken together with the nitrogen to which they are bound form a five or six membered heterocyclic ring;

[0165] (O) R²² is selected from: heterocycloalkyl, alkyl or aryl, wherein said aryl group is optionally substituted with 1 to 3 groups independently selected from halogen, —CF₃, —OCF₃, hydroxyl, or methoxy;

[0166] (P) R²⁴ is selected from: hydrogen, alkyl, —SO₂R²², or aryl, wherein said aryl group is optionally substituted with 1 to 3 groups independently selected from halogen, —CF₃, —OCF₃, hydroxyl, or methoxy;

[0167] (Q) a is 0 to 2;

[0168] (R) b is 0 to 2;

[0169] (S) k is 1 to 5;

[0170] (T) m is 2 to 5;

[0171] (U) n is 1, 2 or 3 with the proviso that when M¹ is N, then n is not 1;

[0172] (V) p is 1, 2 or 3 with the proviso that when M² is N, then p is not 1;

[0173] (W) q is 1 to 5; and

[0174] (X) r is 1, 2, or 3 with the proviso that when r is 2 or 3, M² is C and p is 1.

[0175] Other H₃ receptor antagonists can be identified by the test method described below.

[0176] Preferred H₃ antagonists are clobenpropit, impromidine, GT-2331, GR-175737, UCL-1199, and those disclosed in U.S. Pat. No. 5,990,147, U.S. patent application Ser. No. 09/978,267 and U,S, Provisional Application No. 60/275,417.

[0177] Muscarinic antagonists, in particular those having m₂ activity, are disclosed in several U.S. patents. U.S. Pat. No. 5,883,096 and a divisional thereof, U.S. Pat. No. 6,037,352, disclose the following compounds:

[0178] including all isomers and pharmaceutically acceptable salts, esters, and solvates thereof,

[0179] wherein one of Y and Z is N and the other is N, CH, or C-alkyl;

[0180] X is —O—, —S—, —SO—, —SO₂—, —NR⁶—, —CO—, —CH₂—, —CS—, —C(OR⁵)₂—, —C(SR⁵)₂—, —CONR²⁰—, —C(alkyl)₂—, —C(H)(alkyl)—, —NR²⁰—SO₂—, —NR²⁰CO—,

[0181] hydrogen, acyl, alkyl, alkenyl, cycloalkyl, cycloalkyl substituted with up to two alkyl groups, cycloalkenyl, bicycloalkyl, arylalkenyl, benzyl, benzyl substituted with up to three independently selected R³ groups, cycloalkylalkyl, polyhaloacyl, benzyloxy-alkyl, hydroxyC₂-C₂₀alkyl, alkenylcarbonyl, alkylarylsulfonyl, alkoxycarbonylamino-acyl, alkylsulfonyl, or arylsulfonyl, additionally, when X is —CH₂—, R may also be —OH; in further addition, when X is not N, R may also be hydroxymethyl, in further addition, R and X may combine to form the group Prot-(NOAA)_(r)—NH— wherein r is an integer of 1 to 4, Prot is a nitrogen protecting group and when r is 1, NOAA is a naturally occuring amino acid or an enantiomer thereof, or when r is 2 to 4, each NOAA is a peptide of an independently selected naturally occuring amino acid or an enantiomer thereof;

[0182] R¹ and R²¹ are independently selected from the group consisting of alkyl, alkenyl, cycloalkyl, cycloalkenyl, bicycloalkyl, alkynyl, cyano, aminoalkyl, alkoxycarbonyl, aminocarbonyl, hydroxyguanidino, alkoxycarbonylalkyl, phenyl alkyl, alkylcarbonlyoxyalkyl,

[0183] H, —OH, (provided R¹ and R²¹ are both not —OH and Y is not N), formyl, —CO alkyl, —COacyl, —COaryl, and hydroxyalkyl; additionally R¹ and R²¹ together may form the group

[0184] ═CH₂, ═N—OR⁵, ═N—CN, ═N—N(R⁵)₂, ═CH-Alkyl, alkylene, ═O, ═

[0185] 50 C(halo)₂, in further addition, R¹ and R²¹ together with the carbon atom to which

[0186] they are attached may form the group

[0187] or R¹ and R²¹ together with the carbon atom to which they are attached may form a saturated heterocyclic ring containing 3 to 7 carbon atoms and one group selected from S, O, and NH;

[0188] R² is H, alkyl, alkenyl, cycloalkyl, cycloalkyl substituted with 1 to 3 independently selected R³ groups, cycloalkenyl, hydroxyC₂-C₂₀alkyl, alkynyl, alkylamide, cycloalkylalkyl, hydroxyarylalkyl, bicycloalkyl, alkynyl, acylaminoalkyl, arylalkyl, hydroxyalkoxyalkyl, azabicyclo, alkylcarbonyl. alkoxyalkyl, aminocarbonylalkyl, alkoxycarbonylaminoalkyl, alkoxycarbonylamino(alkyl)alkyl; alkylcarbonyloxyalkyl, arylhydroxyalkyl, alkylcarbonylamino(alkyl)alkyl, dialkylamino,

[0189] (wherein q is an integer of 0 to 2)

[0190] wherein n is 1-3

[0191] wherein m is an integer of 4 to 7,

[0192] wherein t is an integer of 3 to 5,

[0193] (wherein R²⁹ is H, alkyl, acyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylsulfonyl, arylsulfonyl),

[0194] (wherein Q is O, NOH, or NO-alkyl), or when Z is —CH—, R² may also be alkoxycarbonyl, hydroxymethyl, —N(R⁸)₂;

[0195] R³, R⁴, R²², R²⁴, and R²⁵ are independently selected from the group consisting of H, halo, alkoxy, benzyloxy, benzyloxy substituted by nitro or aminoalkyl, haloalkyl, polyhaloalkyl, nitro, cyano, sulfonyl, hydroxy, amino, alkylamino, formyl, alkylthio, polyhaloalkoxy, acyloxy, trialkylsilyl, alkylsulfonyl, arylsulfonyl, acyl, alkoxycarbonyl alkylsulfinyl; —OCONH₂, —OCONH-alkyl, —OCON(alkyl)₂, —NHCOO-alkyl, —NHCO-alkyl, phenyl, hydroxyalkyl, or morpholino;

[0196] each R⁵ and R⁶ is independently selected from the group consisting of H and alkyl, provided that when X is C(OR⁵)₂ or C(SR⁵)_(2,) both R⁵ groups cannot be H, and in addition, when X is C(OR⁵)₂ or C(SR⁵)₂, the two R⁵ groups in X may be joined to form —(CH₂)_(p)— wherein p is an integer of 2 to 4;

[0197] R⁷ is independently selected from the group consisting of H, alkyl, arylalkyl, cycloalkyl, aryl and aryl substituted with R³ and R⁴ as defined herein;

[0198] each R⁸ is independently selected from the group consisting of H, hydroxyalkyl, or alkyl or two R⁸ groups may be joined to form an alkylene group;

[0199] R⁹ is H, alkyl, or acyl;

[0200] R²⁰ is H, phenyl or alkyl; and

[0201] R²⁷ and R²⁸ are independently selected from the group consisting of H, alkyl, hydroxyalkyl, arylalkyl, aminoalkyl, haloalkyl, thioalkyl, alkylthioalkyl, carboxyalkyl, imidazolyalkyl, and indolyalkyl, additionally R²⁷ and R²⁸ may combine to form an alkylene group.

[0202] U.S. Pat. No. 5,889,006 and a divisional thereof, U.S. Pat. No. 6,043,255, disclose compounds of the formula

[0203] Wherein R, R¹, R³, R⁴, R²¹, R²⁷, and R²⁸ are as described in U.S. Pat. No. 5,883,096, but wherein R² is:

[0204] Wherein

[0205] R²⁹ is H, alkyl, —CO-alkyl, alkoxycarbonyl, aminocarbonyl, aryloxycarbonyl alkylaminocarbonyl, dialkylaminocarbonyl, alkylsulfonyl, or arysulfonyl;

[0206] R³⁰ is H, alkyl, aryl, cycloalkyl, hydroxyalkyl, aminoalkyl, —COOR²⁰, —CON(R²⁰)₂ or cyano;

[0207] R³¹ and R³² are the same as R³⁰ and in addition, two R³⁰, R³¹ and R³² groups may form the group —(CH₂)_(r)—(wherein r is 1 to 6), in further addition, R³¹ and R³² can also be hydroxy, —N(R²⁰)₂, —O-acyl, —N(R²⁰)acyl, —OCOOR²⁰, or —OCON(R²⁰) ₂;

[0208] R³³ is aryl or heteroaryl, with the proviso that when R³³ is heteroaryl, the CO—R³³ bond is to a carbon atom in the R³³ group; and

[0209] R³⁴ is alkyl, cycloalkyl or aryl and in addition R³⁴ may also be H when R¹ and R²¹ together with the carbon atom to which they are attached form a saturated heterocyclic ring containing 3 to 7 carbon atoms and two groups independently selected from S, O, and N—R²⁰.

[0210] U.S. Pat. No. 5,952,349 discloses the following compounds:

[0211] or an isomer, pharmaceutically acceptable salt, ester or solvate thereof, wherein

[0212] X is a bond, —O—, —S—, —SO—, —SO₂—, —CO—, —C(OR⁷)₂—, —CH₂—O—, —O—CH₂—, —CH═CH—, —CH₂—, —CH(C₁-C₆ alkyl)—, —C(C₁-C₆ alkyl)₂—, —CONR¹⁷—, —NR¹⁷CO—, —SO₂NR¹⁷— or —NR¹⁷SO₂—;

[0213] R is C₃-C₆ cycloalkyl,

[0214] R¹ is H, —CN, —CF₃, C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₃-C₆ cycloalkenyl, C₃-C₆ alkenyl, —COR¹⁵, —COO(C₁-C₆ alkyl), —COO(aryl), —COO(heteroaryl), —COO((C₁-C₆ alkyl)aryl), —COO((C₁-C₆ alkyl)heteroaryl), —(C₁-C₆ alkyl)aryl, —(C₁-C₆ alkyl)heteroaryl or —CON(R¹³)₂;

[0215] R² is C₃-C₆ cycloalkyl, C₃-C₆ cycloalkenyl, t-butoxycarbonyl or

[0216] R³ and R⁴ are independently selected from the group consisting of H, halo, —CF₃, C₁-C₆ alkyl, C₁-C₆ alkoxy and —OH;

[0217] R⁵ and R⁶ are independently selected from the group consisting of H, C₁-C₆ alkyl, —CF₃, C₁-C₆ alkoxy, —OH, C₁-C₆ alkylcarbonyl, C₁-C₆ alkoxycarbonyl, R¹³CONH—, R¹⁴OCONH—, R¹³NHCONH— and NH₂CONR^(13—);

[0218] R⁷ is independently selected from the group consisting of H and alkyl, provided that both R⁷ groups are not H; or the two R⁷ groups may be joined to form —(CH₂)_(p)— wherein p is an integer of 2 to 4;

[0219] R⁸, R⁹, R¹⁰, R¹¹ and R¹² are independently selected from the group consisting of H, halo, C₁-C₆ alkyl, C₁-C₆ alkoxy, benzyloxy, benzyloxy substituted by —NO₂ or —N(R¹⁴), halo C₁-C₆ alkyl, polyhalo C₁-C₆ alkyl, —NO₂, —CN, —SO₂, —OH, —NH₂, —N(R¹⁴)₂, —HCO, polyhalo C₁-C₆ alkoxy, acyloxy, (C₁-C₄ alkyl)₃Si—, (C₁-C₆ alkyl)SO₀₋₂, arylsulfonyl, heteroaryl-sulfonyl, acyl, (C₁-C₆ alkoxy)CO—, —OCON(R¹⁴)₂, —NHCOO—(C₁-C₆)alkyl, —NHCO—(C₁-C₆ alkyl), phenyl, hydroxy(C₁-C₆ alkyl) or morpholino;

[0220] R¹³ is independently selected from the group consisting of H, C₁-C₆ alkyl, C₃-C₆ cycloalkyl, —(C₁-C₆ alkyl)COOR¹⁵, aryl, heteroaryl, —(C₁-C₆ alkyl)aryl, —(C₁-C₆ alkyl)heteroaryl and adamantyl;

[0221] R¹⁴ is independently selected from the group consisting of H and C₁-C₆ alkyl;

[0222] R¹⁵ is H, C₁-C₂₀ alkyl, C₁-C₆ cycloalkyl, aryl or heteroaryl;

[0223] R¹⁶ is H, C₁-C₆ alkyl, —COR¹⁵, C₁-C₆ alkoxycarbonyl, (R¹⁴)₂NCO— or —SO₁₋₂—R¹⁵; and

[0224] R¹⁷ is H, C₁-C₆ alkyl, aryl or heteroaryl.

[0225] U.S. Pat. No. 5,935,958 discloses the following compounds:

[0226] including all stereoisomers and pharmaceutically acceptable salts, esters, and solvates thereof, wherein:

[0227] Z is N, CH or C-alkyl;

[0228] X is —O—, —S—, —SO—, —SO₂—, —CO—, —CH₂—, —CONR²⁰—, —NR²⁰—SO₂—, —NR²⁰CO—, or —SO₂—NR²⁰—;

[0229] Q is —O—, —S—, —SO—, —SO₂—, or —CH₂—;

[0230] R is

[0231] R¹ and R²¹ are independently selected from the group consisting of hydrogen, alkyl, alkenyl, cycloalkyl, cycloalkenyl, cycloalkylalkyl, cycloalkenylalkyl, phenylalkyl, and hydroxyalkyl;

[0232] R² is cycloalkyl, cycloalkyl substituted with 1 to 3 independently selected R³ groups, cycloalkenyl, cycloalkylalkyl,

[0233] (wherein R^(y) is H, alkyl, alkenyl, SO₂R^(z) or COR^(z) wherein R^(z) is alkyl, alkenyl, aryl, heteroaryl, or cycloalkyl), with the proviso that R² is R³-substituted-1-piperidinyl only when Z is CH or C-alkyl; or, when Z is CH, R² may also be alkoxycarbonyl, —N(R⁹)(hydroxyalkyl) wherein R⁹ is H, hydroxyalkyl, or alkyl, or —N(R⁹)₂ wherein the two R⁹ groups may be joined to form an alkylene group;

[0234] R³, R⁴, R⁵, R⁶, R²², R²⁴, and R²⁵ are independently selected from the group consisting of H, alkyl, halo, alkoxy, benzyloxy, benzyloxy substituted by nitro or aminoalkyl, polyhaloalkyl, nitro, sulfonyl, hydroxy, amino, alkylamino, formyl, alkylthio, acyloxy, alkylsulfonyl, arylsulfonyl, acyl, alkoxycarbonyl, alkylsulfinyl, —OCONH₂, —OCONH-alkyl, —OCON(alkyl)₂, —NHCOO-alkyl, —NHCO-alkyl, phenyl, hydroxyalkyl, and 1-morpholinyl;

[0235] R⁸ is hydrogen, lower alkyl or cyclopropyl;

[0236] R²⁰ is H, phenyl or alkyl;

[0237] R²⁷ and R²⁸ are independently selected from the group consisting of H, alkyl, hydroxyalkyl, alkoxyalkyl, arylalkyl, mercaptoalkyl, alkylthioalkyl, and carboxyalkyl, and additionally R²⁷ and R²⁸ may be joined to form an alkylene group; and

[0238] n is 0 or an integer from 1 to 3.

[0239] U.S. Pat. No. 6,066,636 discloses the following compounds:

[0240] including all stereoisomers and pharmaceutically acceptable salts and solvates thereof,

[0241] wherein one of Y and Z is —N— and the other is —N— or —CH—;

[0242] X is —O—, —S—, —SO—, —SO₂— or —CH₂—;

[0243] Q is

[0244] R is (C₁-C₂₀)alkyl, (C₃-C₁₂)cycloalkyl, aryl, R⁸-aryl or heteroaryl;

[0245] R¹, R² and R³ are independently selected from the group consisting of H and (C₁-C₂₀)alkyl;

[0246] R⁴ is (C₁-C₂₀)alkyl, (C₃-C₁₂)cyclolalkyl or

[0247] R⁵ is H, (C₁-C₂₀)alkyl, —C(O)(C₁-C₂₀)alkyl, R⁹-arylcarbonyl, —SO₂(C₁-C₂₀)alkyl, R⁹-arylsulfonyl —C(O)O(C₁-C₂₀)alkyl, R⁹-aryloxy-carbonyl, —C(O)NH—(C₁-C₂₀)alkyl or R⁹-arylaminocarbonyl;

[0248] R⁶ is H or (C₁-C₂₀)alkyl;

[0249] R⁷ is H, (C₁-C₂₀)alkyl, hydroxy(C₁-C₂₀)alkyl or (C₁-C₂₀)-alkoxy (C₁-C₂₀)alkyl;

[0250] R⁸ is 1-3 substituents independently selected from the group consisting of H, (C₁-C₂₀)alkyl, halogen, hydroxy, (C₁-C₂₀)alkoxy or hydroxy(C₁-C₂₀)alkyl, or two adjacent R⁸ groups may be joined to form a (C₁-C₂)alkylenedioxy group; and

[0251] R⁹ is 1-3 substituents independently selected from the group consisting of H, (C₁-C₂₀)alkyl, halogen, amino or (C₁-C₂₀)alkylamino.

[0252] U.S. Pat. No. 5,977,138 discloses the following compounds:

[0253] or an isomer, pharmaceutically acceptable salt, ester or solvate thereof, wherein

[0254] X is a bond, —O—, —S—, —SO—, —SO₂—, —CO—, —C(OR⁷)₂—, —CH₂—O—, —O—CH₂—, —CH═CH—, —CH₂—, —CH(C₁-C₆ alkyl)—, —C(C₁-C₆ alkyl)₂—, —CONR¹⁷—, —NR¹⁷CO—, —O—C(O)NR¹⁷—, —NR¹⁷C(O)—O—, —SO₂NR¹⁷— or —NR¹⁷SO₂—;

[0255] R is C₃-C₆ cycloalkyl,

[0256] n is 1, 2 or 3;

[0257] R² is H, C₂-C₇ alkyl, C₃-C₇ cycloalkyl, C₃-C₇ cycloalkyl substituted by 1 to 4 groups independently selected from R¹⁸, C₃-C₆ cycloalkenyl, t-butoxycarbonyl or

[0258] R³ and R⁴ are independently selected from the group consisting of H, halo, —CF₃, C₁-C₆ alkyl, C₁-C₆ alkoxy and —OH;

[0259] R⁵ and R⁶ are independently selected from the group consisting of H, C₁-C₆ alkyl, —CF₃, C₁-C₆ alkoxy, —OH, C₁-C₆ alkylcarbonyl, C₁-C₆ alkoxycarbonyl, R¹³CONH—, (R¹³)₂NCO—, R¹³OCONH—, R¹³NHCONH— and NH₂CONR¹³—;

[0260] R⁷ is independently selected from the group consisting of C₁-C₆ alkyl; or the two R⁷ groups may be joined to form —(C(R¹⁴)₂)_(p)— wherein p is an integer from 2-4;

[0261] R⁸, R⁹, R¹⁰, R¹¹ and R¹² are independently selected from the group consisting of H, halo, C₁-C₆ alkyl, C₁-C₆ alkoxy, benzyloxy, benzyloxy substituted by —NO₂ or —N(R¹⁴), halo C₁-C₆ alkyl, polyhalo C₁-C₆ alkyl, —NO₂, —CN, —SO₂, —OH, —NH₂, —N(R¹⁴)₂, —CHO, polyhalo C₁-C₆ alkoxy, acyloxy, (C₁-C₄ alkyl)₃Si—, (C₁-C₆ alkyl)SO₀₋₂, arylsulfonyl, heteroaryl-sulfonyl, acyl, (C₁-C₆ alkoxy)CO—, —OCON(R¹⁴)₂, —NHCOO—(C₁-C₆)alkyl, —NHCO—(C₁-C₆ alkyl), phenyl, hydroxy(C₁-C₆ alkyl) or morpholino;

[0262] R¹³ is independently selected from the group consisting of H, C₁-C₆ alkyl, C₃-C₆ cycloalkyl, —(C₁-C₆ alkyl)COOR¹⁵, aryl, heteroaryl, —(C₁-C₆ alkyl)aryl, —(C₁-C₆ alkyl)heteroaryl and adamantyl;

[0263] R¹⁴ is independently selected from the group consisting of H and C₁-C₆ alkyl;

[0264] R¹⁵ is independently selected from the group consisting of H, C₁-C₂₀ alkyl, C₃-C₆ cycloalkyl, aryl substituted by 1 to 3 groups independently selected from R³ and heteroaryl substituted by 1 to 3 groups independently selected from R³;

[0265] R¹⁶ is H, C₁-C₆ alkyl, —COR²⁰, C₁-C₆ alkoxycarbonyl, —CON(R¹⁴)₂, —CONH(R³-aryl), —SO₁₋₂—R¹⁵, —SO₁₋₂—(CH₂)_(m)—R²¹, —SON(R¹⁴)₂, —COSR¹⁴ or

[0266] R¹⁷ is H, C₁-C₆ alkyl, aryl or heteroaryl;

[0267] R¹⁸ is independently selected from the group consisting of halo, —CF₃, C₁-C₆ alkyl, C₁-C₆ alkoxy, —OH, ═O, —CON(R¹⁴)₂ and —N(R¹⁴)COR¹⁵;

[0268] R¹⁹ is H, —OH, C₁-C₂₀ alkyl, C₃-C₆ cycloalkyl, aryl substituted by 1 to 3 groups independently selected from R³ or heteroaryl substituted by 1 to 3 groups independently selected from R³;

[0269] R²⁰ is H, C₁-C₂₀ alkyl, C₁-C₆ alkoxy(C₁-C₆)alkyl, C₃-C₆ cycloalkyl, aryl, aryl(C₁-C₆ alkyl)—, aryloxy, aryloxy(C₁-C₆ alkyl)—, tetrahydrofuranyl or heteroaryl, wherein the aryl or heteroaryl group is substituted by 1 to 3 groups independently selected from R³;

[0270] m is 0 to 3; and

[0271] R²¹ is C₇-C₁₀ bridged cycloalkyl or C₇-C₁₀ bridged cycloalkyl wherein the cycloalkyl portion is substituted by 1 or 2 substituents selected from the group consisting of C₁-C₆ alkyl or ═O.

[0272] A genus of selective m₂ muscarinic antagonists, disclosed in U.S. Pat. No. 6,294,554 B1, has the following structural formula:

[0273] or a pharmaceutically acceptable salt, ester or solvate thereof, wherein

[0274] Q and Q¹ are each —CH═, or one of Q and Q¹ is —CH═ and the other is —N═;

[0275] X is —CH₂— or

[0276] Y and Z are independently selected from the group consisting of —C(R⁵)═, or one of Y and Z is —C(R⁵)═ and the other is —N═;

[0277] R¹ is 1 to 3 substituent independently selected from the group consisting of H, halogen and (C₁-C₆)alkoxy;

[0278] R² and R⁵ are independently 1 to 3 substituents independently selected from the group consisting of H, halogen, (C₁-C₆)alkyl and (C₁-C₆)alkoxy; and

[0279] R³ and R⁴ are independently selected from the group consisting of H and (C₁-C₆)alkyl.

[0280] Of those compounds, preferred are compounds wherein both Y and Z are —C(R⁵)═, and wherein R⁵ is preferably H, methyl or halogen. Also preferred are compounds wherein Y is —CH═, Z is —N═ and R² is hydrogen. R¹ is preferably halogen, more preferably chloro, or methoxy, and in particular, R¹ is 3-chloro or 4-methoxy. Q and Q¹ are preferably each —CH═. Preferred R² substituents are Cl, F and methyl, with 3-methyl being more preferred. R³ and R⁴ are preferably each H.

[0281] U.S. Provisional Application No. 60/257,853, filed Dec. 22, 2000 discloses compounds having the following structure:

[0282] or a pharmaceutically acceptable salt, ester or solvate thereof, wherein

[0283] R¹ is R⁵—(C₃-C₈)cycloalkyl, R⁵—(C₃-C₈)cycloalkyl(C₁-C₆)alkyl, R⁵-aryl, R⁵-aryl-(C₁-C₆)alkyl or R⁵-heteroaryl;

[0284] R² is H, (C₁-C₆)alkyl, R⁶—(C₃-C₈)cycloalkyl, R⁶—(C₃-C₈) cycloalkyl-(C₁-C₆)alkyl, R⁶-heterocycloalkyl, R⁶—(C₆-C₁₀)bridged cycloalkyl, or R⁶-bridged heterocycloalkyl;

[0285] R³ is C₁-C₆ alkyl or —CH₂OH;

[0286] R⁴ is H or C₁-C₆ alkyl;

[0287] R⁵ is 1-4 substituents independently selected from the group consisting of H, C₁-C₆ alkyl, halogen, —OH, C₁-C₆ alkoxy, CF₃, —CN, —CO₂R⁴, —CONHR⁴, —SO₂NHR⁴, —NHSO₂R⁴ and —NHC(O)R⁴; and

[0288] R⁶ is 1-4 substituents independently selected from the group consisting of H, C₁-C₆ alkyl, halogen, —OH, C₁-C₆ alkoxy, CF₃, —NH₂, (C₁-C₆)alkylamino, phenyl, C₁-C₂ alkylenedioxy, and (C₁-C₆)alkoxycarbonyl.

[0289] U.S. Provisional Application No. 60/328,356, filed Oct. 10, 2001 discloses compounds having the following structure:

[0290] including enantiomers, stereoisomers, rotamers, tautomers and prodrugs of said compound, or pharmaceutically acceptable salts, esters or solvates of said compound or of said prodrugs, wherein:

[0291] Z is N, CH, or C-alkyl;

[0292] X is —O—, —S—, —SO—, —SO₂—, —CO—, —CH₂—, or —CS;

[0293] R is

[0294] R² is

[0295] R³ is alkoxy or halo;

[0296] R⁴ is hydrogen, alkyl or alkylhalide;

[0297] R²⁷ and R²⁸ are independently selected from the group consisting of H, alkyl, hydroxyalkyl, arylalkyl, aminoalkyl, haloalkyl, thioalkyl, alkylthioalkyl, carboxyalkyl, imidazolyalkyl, and indolyalkyl; or R²⁷ and R²⁸ may combine to form an alkylene group;

[0298] R²⁹ is H, alkyl, —CO-alkyl, —CO-cycloalkyl, alkoxycarbonyl, amino-carbonyl, aryloxycarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylsulfonyl, arysulfonyl or —SO₂—NH—R³⁵;

[0299] R³¹ and R³² are each independently H, alkyl, aryl, cycloalkyl, hydroxyalkyl, or aminoalkyl, and in addition, R³¹ and R³² can form the group —(CH₂)_(r)—(wherein r is 1 to 6), in further addition, R³¹ and R³² can also be hydroxy, —N(R ³⁵)₂, —O-acyl, —N(R³⁵)acyl, —OCOOR³⁵, or —OCON(R³⁵)₂;

[0300] R³³ is aryl or heteroaryl, with the proviso that when R³³ is heteroaryl, the CO—R³³ bond is to a carbon atom in the R³³ group; and

[0301] R³⁵ is H, aryl or alkyl.

[0302] Preferred m₂ antagonists are those claimed in U.S. Pat. No. 6,043,255.

[0303] An especially preferred m₂ antagonist has the structure

[0304] The U.S. patents and applications cited herein are incorporated herein by reference.

[0305] Other m₂ antagonists can be identified by the test methods described below.

[0306] The H₃ antagonist and m₂ antagonist compounds are prepared by known methods. The dual H₃/m₂ antagonists listed above are prepared by methods described in the m₂ antagonist patents listed above.

[0307] The combination of H₃ and m₂ antagonists can also comprise more than one H₃ antagonist (e.g., 2-3) and/or more than one m₂ antagonist (e.g., 2-3).

[0308] In the aspect of the invention relating to a combination of a dual H₃/m₂ antagonist in combination with an acetylcholinesterase inhibitor, or a combination of an H₃ antagonist and a m₂ antagonist with an acetylcholinesterase inhibitor, examples of acetylcholinesterase inhibitors are donepezil, heptylphysostigmine, tacrine, rivastigmine and galantamine.

[0309] Test Methods:

[0310] Compounds can readily be evaluated to determine activity at H₃ receptors by known methods, including the guinea pig brain membrane assay and the guinea pig neurogenic ileum contraction assay, both of which are described in U.S. Pat. No. 5,352,707. Another useful assay utilizes rat brain membranes and is described by West et al., “Identification of Two H₃-Histamine Receptor Subtypes,” Molecular Pharmacology, Vol. 38, pages 610-613 (1990).

[0311] A particularly useful screening assay measures binding to sites in guinea pig brain membranes. This test is described in detail by Korte et al., “Characterization and Tissue Distribution of H₃ Histamine Receptors in Guinea Pigs by N^(α)-Methylhistamine,” in Biochemical and Biophysical Research Communications, Vol. 168, pages 979-986 (1990), and quantifies the displacement of bound radiolabeled N^(α)-methylhistamine from tissues by candidate compounds. Results are expressed as “K_(i)” values, in nanoMolar (nM) units, which values can be considered as being dissociation constants for the H₃ antagonist on the H₃ receptor system, or an index of antagonist affinity for the receptor. In general, K_(l)values less than about 200 nM are considered necessary for an agent to be useful as an H₃ antagonist in the invention. More preferably, the agent will exhibit K_(i) values of 100 nM or less.

[0312] The compound of interest also is tested for its ability to inhibit binding to the cloned human m₁, m₂ and m₄ muscarinic receptor subtypes. The sources of receptors in these studies were membranes from stably transfected CHO cell lines which were expressing each of the receptor subtypes. Following growth, the cells were pelleted and subsequently homogenized using a Polytron in 50 volumes cold 10 mM Na/K phosphate buffer, pH 7.4 (Buffer B). The homogenates were centrifuged at 40,000×g for 20 minutes at 4° C. The resulting supernatants were discarded and the pellets were resuspended in Buffer B at a final concentration of 20 mg wet tissue/ml. These membranes were stored at −80° C. until utilized in the binding assays described below.

[0313] Binding to the cloned human muscarinic receptors was performed using ³H-quinuclidinyl benzilate (QNB) (Watson et al., 1986). Briefly, membranes (approximately 8, 20, and 14 μg of protein assay for the m₁, m₂, and m₄ containing membranes, respectively) were incubated with ³H-QNB (final concentration of 100-200 pM) and increasing concentrations of unlabeled drug in a final volume of 2 ml at 25° C. for 90 minutes. Non-specific binding was assayed in the presence of 1 μM atropine. The incubations were terminated by vacuum filtration over GF/B glass fiber filters using a Skatron filtration apparatus and the filters were washed with cold 10 mM Na/K phosphate butter, pH 7.4. Scintillation cocktail was added to the filters and the vials were incubated overnight. The bound radioligand was quantified in a liquid scintillation counter (50% efficiency). The resulting data were analyzed for IC₅₀ values (i.e. the concentration of compound required to inhibit binding by 50%) using the EBDA computer program (McPherson, 1985).

[0314] Affinity values (K_(i)) are determined using the following formula; $K_{i} = \frac{{IC}_{50}}{1 + \left\lbrack \frac{{concentration}\quad {of}\quad {radioligand}}{\text{affinity}\quad \left( K_{D} \right)\quad \text{of~~radioligand}} \right\rbrack}$

[0315] Hence, a lower value of K_(i) indicates greater binding affinity.

[0316] To determine the degree of selectivity of a compound for binding the m₂ receptor, the K_(i) value for m₁ receptors was divided by the K_(i) value for m₂ (or m₄) receptors. A higher ratio indicates a greater selectivity for binding the m₂ muscarinic receptor.

[0317] The following procedure is used to show that a compound functions as a m₂ antagonist.

[0318] Surgery:

[0319] For these studies, male Sprague-Dawley Rats (250-350 g) were anesthetized with sodium pentobarbital (54 mg/kg, ip) and placed on a Kopf sterotaxic apparatus. The skull was exposed and drilled through to the dura at a point 0.2 mm anterior and 3.0 mm lateral to the bregma. At these coordinates, a guide cannula was positioned at the outer edge of the dura through the drilled opening, lowered perpendicularly to a depth of 2.5 mm, and permanently secured with dental cement to bone screws. Following the surgery, rats were given ampicillin (40 mg/kg, ip) and individually housed in modified cages. A recovery period of approximately 3 to 7 days was allowed before the microdialysis procedure was undertaken.

[0320] Microdialysis:

[0321] All of the equipment and instrumentation used to conduct in vivo microdialysis was obtained from Bioanalytical Systems, Inc. (BAS). The microdialysis procedure involved the insertion through the guide cannula of a thin, needle-like perfusable probe (CMA/12,3 mm×0.5 mm) to a depth of 3 mm in striatum beyond the end of the guide. The probe was connected beforehand with tubing to a microinjection pump (CMA/100). Rats were collared, tethered, and, following probe insertion, were placed in a large, clear, plexiglass bowl with litter material and access to food and water. The probe was perfused at 2 μl/min with Ringer's buffer (NaCl 147 mM; KCI 3.0 mM; CaCl₂ 1.2 mM; MgCl₂ 1.0 mM) containing 5.5 mM glucose, 0.2 mM L-ascorbate, and 1 μM neostigmine bromide at pH 7.4). To achieve stable baseline readings, microdialysis was allowed to proceed for 90 minutes prior to the collection of fractions. Fractions (20 μl) were obtained at 10 minute intervals over a 3 hour period using a refrigerated collector (CMA/170 or 200). Four to five baseline fractions were collected, following which the drug or combination of drugs to be tested was administered to the animal. Upon completion of the collection, each rat was autopsied to determine accuracy of probe placement.

[0322] Acetylcholine (ACh) Analysis:

[0323] The concentration of ACh in collected samples of microdialysate was determined using HPLC/electrochemical detection. Samples were auto-injected (Waters 712 Refrigerated Sample Processor) onto a polymeric analytical HPLC column (BAS, MF-6150) and eluted with 50 mM Na₂HPO₄, pH 8.5. To prevent bacterial growth, Kathon CG reagent (0.005%) (BAS) was included in the mobile phase. Eluent from the analytical column, containing separated ACh and choline, was then immediately passed through an immobilized enzyme reactor cartridge (BAS, MF-6151) coupled to the column outlet. The reactor contained both acetylcholinesterase and choline oxidase covalently bound to a polymeric backbone. The action of these enzymes on ACh and choline resulted in stoichiometric yields of hydrogen peroxide, which was electrochemically detected using a Waters 460 detector equipped with a platinum electrode at a working potential of 500 mvolts. Data acquisition was carried out using an IBM Model 70 computer equipped with a microchannel IEEE board. Integration and quantification of peaks were accomplished using “Maxima” chromatography software (Waters Corporation). Total run time per sample was 11 minutes at a flow rate of 1 ml/min. Retention times for acetylcholine and choline were 6.5 and 7.8 minutes, respectively. To monitor and correct for possible changes in detector sensitivity during chromatography, ACh standards were included at the beginning, middle and end of each sample queue.

[0324] Increases in ACh levels are consistent with presynaptic m₂ receptor antagonism.

[0325] Affinity values for the H₃ and m₂ receptors were determined for the dual antagonists identified above. The results of the test procedures are as follows: Compound H₃ m₂ Number Ki Ki 1 18 0.17 2 140 0.01 3 500 0.125 4 620 3.4 5 430 2.6 6 160 1.2 7 22 0.07 8 6 0.05 9 290 0.22 10 15 0.019 11 8 0.018 12 170 4.8 13 12 0.8 14 2 0.7 15 43 0.17

[0326] For preparing pharmaceutical compositions from the compounds described by this invention, inert, pharmaceutically acceptable carriers can be either solid or liquid. Solid form preparations include powders, tablets, dispersible granules, capsules, cachets and suppositories. The powders and tablets may be comprised of from about 5 to about 95 percent active ingredient. Suitable solid carriers are known in the art, e.g. magnesium carbonate, magnesium stearate, talc, sugar, lactose. Tablets, powders, cachets and capsules can be used as solid dosage forms suitable for oral administration.

[0327] For preparing suppositories, a low melting wax such as a mixture of fatty acid glycerides or cocoa butter is first melted, and the active ingredient is dispersed homogeneously therein as by stirring. The molten homogeneous mixture is then poured into convenient sized molds, allowed to cool and thereby solidify.

[0328] Liquid form preparations include solutions, suspensions and emulsions. As an example may be mentioned water or water-propylene glycol solutions for parenteral injection.

[0329] Liquid form preparations may also include solutions for intranasal administration.

[0330] Aerosol preparations suitable for inhalation may include solutions and solids in powder form, which may be in combination with a pharmaceutically acceptable carrier, such as an inert compressed gas.

[0331] Also included are solid form preparations which are intended to be converted, shortly before use, to liquid form preparations for either oral or parenteral administration. Such liquid forms include solutions, suspensions and emulsions.

[0332] The compounds of the invention may also be deliverable transdermally. The transdermal compositions can take the form of creams, lotions, aerosols and/or emulsions and can be included in a transdermal patch of the matrix or reservoir type as are conventional in the art for this purpose.

[0333] Preferably the compound or combination is administered orally.

[0334] Preferably, the pharmaceutical preparation comprising a dual H₃/m₂ antagonist is in unit dosage form. In such form, the preparation is subdivided into unit doses containing appropriate quantities of the active component, e.g., an effective amount to achieve the desired purpose.

[0335] The quantity of active dual H₃/m₂ antagonist compound in a unit dose of preparation may be varied or adjusted from about 1 mg to 100 mg, preferably from about 1 mg. to 50 mg, more preferably about 1 to about 25 mg, according to the particular application.

[0336] The actual dosage employed may be varied depending upon the requirements of the patient and the severity of the condition being treated. Determination of the proper dosage for a particular situation is within the skill of the art. Generally, treatment is initiated with smaller dosages which are less than the optimum dose of the compound. Thereafter, the dosage is increased by small increments until the optimum effect under the circumstances is reached. For convenience, the total daily dosage may be divided and administered in portions during the day if desired.

[0337] The amount and frequency of administration of the dual compounds of the invention and the pharmaceutically acceptable salts thereof will be regulated according to the judgment of the attending clinician considering such factors as age, condition and size of the patient as well as severity of the symptoms being treated. A typical recommended dosage regimen for dual H₃/m₂ antagonist is oral administration of from 1 mg to 300 mg/day, preferably 1 to 50 mg/day, in two to four divided doses to provide relief from cognition deficit disorders such as Alzheimer's disease.

[0338] When the invention comprises a combination of separate H₃ antagonist and m₂ antagonist compounds, the two active components may be co-administered simultaneously or sequentially, or a single pharmaceutical composition comprising a H₃ antagonist and an m₂ antagonist in a pharmaceutically acceptable carrier can be administered. The components of the combination can be administered individually or together in any conventional dosage form such as capsule, tablet, powder, cachet, suspension, solution, suppository, nasal spray, etc. The dosage of the H₃ antagonist can be determined from published material, and may range from 1 to 1000 mg per dose. The m₂ antagonist can be administered in a dosage range of 1 mg to about 100 mg, preferably from about 1 mg. to 50 mg, and more preferably about 1 to about 25 mg. When used in combination, the dosage levels of the individual components are preferably lower than the recommended individual dosages because of the advantageous effect of the combination.

[0339] The dosage of the acetylcholinesterase inhibitor used in a combination may range from 0.001 to 100 mg/kg body weight.

[0340] When separate H₃ and m₂ pharmaceutical compositions are to be administered, they can be provided in a kit comprising in a single package, one container comprising an H₃ antagonist in a pharmaceutically acceptable carrier, and a separate container comprising a m₂ antagonist in a pharmaceutically acceptable carrier, with the H₃ and m₂ antagonists being present in amounts such that the combination is effective to treat cognition deficit disorders. When an acetylcholinesterase inhibitor is also administered, a separate container comprising an acetylcholinesterase inhibitor in a pharmaceutically acceptable carrier can also be added to the kit. A kit is advantageous for administering a combination when, for example, the components must be administered at different time intervals or when they are in different dosage forms.

[0341] The compounds are non-toxic when administered within this dosage range.

[0342] The following are examples of pharmaceutical dosage forms which contain a dual compound of the invention, although those skilled in the art will recognize that similar dosage forms will be suitable for separate H₃ and m₂ antagonists, or for combinations of the separate actives. The scope of the invention in its pharmaceutical composition aspect is not to be limited by the examples provided. EXAMPLE A Tablets Pharmaceutical Dosage Form Examples No. Ingredients mg/tablet mg/tablet 1. Active compound 100 500 2. Lactose USP 122 113 3. Corn Starch, Food Grade, as a  30  40 10% paste in Purified Water 4. Corn Starch, Food Grade  45  40 5. Magnesium Stearate  3  7 Total 300 700

Method of Manufacture

[0343] Mix Item Nos. 1 and 2 in a suitable mixer for 10-15 minutes. Granulate the mixture with Item No. 3. Mill the damp granules through a coarse screen (e.g., ¼″, 0.63 cm) if necessary. Dry the damp granules. Screen the dried granules if necessary and mix with Item No. 4 and mix for 10-15 minutes. Add Item No. 5 and mix for 1-3 minutes. Compress the mixture to appropriate size and weigh on a suitable tablet machine. EXAMPLE B Capsules No. Ingredient mg/capsule mg/capsule 1. Active compound 100 500 2. Lactose USP 106 123 3. Corn Starch, Food Grade  40  70 4. Magnesium Stearate NF  7  7 Total 253 700

Method of Manufacture

[0344] Mix Item Nos. 1, 2 and 3 in a suitable blender for 10-15 minutes. Add Item No. 4 and mix for 1-3 minutes. Fill the mixture into suitable two-piece hard gelatin capsules on a suitable encapsulating machine.

[0345] While the present invention has been described in conjunction with the specific embodiments set forth above, many alternatives, modifications and variations thereof will be apparent to those of ordinary skill in the art. All such alternatives, modifications and variations are intended to fall within the spirit and scope of the present invention. 

We claim:
 1. A method of treating cognition deficit disorders comprising administering to a mammal in need of such treatment an effective amount of a dual histamine H₃ receptor antagonist/m₂ muscarinic antagonist.
 2. The method of claim 1 wherein the dual H₃/m₂ antagonist is selected from the group consisting of


3. A method of treating cognition deficit disorders comprising administering to a mammal in need of such treatment an effective amount of a combination of an histamine H₃ receptor antagonist and a m₂ muscarinic antagonist.
 4. The method of claim 3 wherein the histamine H₃ receptor antagonist is selected from the group consisting of thioperamide, impromidine, burimamide, clobenpropit, impentamine, mifetidine, S-sopromidine, R-sopromidine, ciproxifam, SKF-91486, GR-175737, GT-2016, GT-2331, UCL-1199, clozapine and those of formula VIII and IX.
 5. The method of claim 4 wherein the histamine H₃ antagonist is selected from the group consisting of clobenpropit, impromidine, GT-2331, GR-175737, UCL-1199 and those of formula VIII and IX.
 6. The method of claim 3 wherein the m₂ muscarinic antagonist is selected from the compounds of the formula IA-1.
 7. The method of claim 6 wherein the histamine H₃ receptor antagonist is selected from the group consisting of thioperamide, impromidine, burimamide, clobenpropit, impentamine, mifetidine, S-sopromidine, R-sopromidine, ciproxifam, SKF-91486, GR-175737, GT-2016, GT-2331, UCL-1199, clozapine and those of formula VIII and IX.
 8. The method of claim 7 wherein the histamine H₃ antagonist is selected from the group consisting of clobenpropit, impromidine, GT-2331, GR-1 75737, UCL-1199 and those of formula VIII and IX.
 9. The method of claim 3 wherein the histamine H₃ antagonist is selected from the group consisting of clobenpropit, impromidine, GT-2331, GR-1 75737, UCL-1199 and those of formula VIII and IX, and the m₂ antagonist is


10. A pharmaceutical composition comprising an effective amount of a combination of a histamine H₃ antagonist and a m₂ muscarinic antagonist, and a pharmaceutically acceptable carrier.
 11. The composition of claim 10 wherein the histamine H₃ receptor antagonist is selected from the group consisting of thioperamide, impromidine, burimamide, clobenpropit, impentamine, mifetidine, S-sopromidine, R-sopromidine, ciproxifam, SKF-91486, GR-175737, GT-2016, GT-2331, UCL-1199, clozapine and those of formula VIII and IX; and wherein the m₂ muscarinic antagonist is selected from the compounds of formula IA-1.
 12. The composition of claim 11 wherein the histamine H₃ antagonist is selected from the group consisting of clobenpropit, impromidine, GT-2331, GR-175737, UCL-1199 and those of formula VIII and IX and the m₂ antagonist is


13. A kit comprising in a single package, one container comprising a histamine H₃ antagonist in a pharmaceutically acceptable carrier, and a separate container comprising a m₂ muscarinic antagonist in a pharmaceutically acceptable carrier, with the H₃ and m₂ antagonists being present in amounts such that the combination is effective to treat cognition deficit disorders.
 14. A method of treating cognition deficit disorders comprising administering to a mammal in need of such treatment an effective amount of a dual histamine H₃ antagonist/m₂ muscarinic antagonist or an effective amount of a combination of a histamine H₃ receptor antagonist and a m₂ muscarinic antagonist, in combination with an effective amount of an acetylcholinesterase inhibitor.
 15. A pharmaceutical composition comprising an effective amount of a dual histamine H₃ antagonist m₂ muscarinic antagonist or a combination of a histamine H₃ antagonist and a m₂ muscarinic antagonist, in further combination with an acetylcholinesterase inhibitor and a pharmaceutically acceptable carrier.
 16. A kit comprising, in a single package, one container comprising a dual histamine H₃ antagonist/m₂ muscarinic antagonist in a pharmaceutically acceptable carrier, or separate containers comprising a histamine H₃ antagonist in a pharmaceutically acceptable carrier and a m₂ muscarinic antagonist in a pharmaceutically acceptable carrier, and another container comprising an acetylcholinesterase inhibitor in a pharmaceutically acceptable carrier. 